Asphalt based roofing shingles are presently installed on approximately eighty percent of the homes in the United States. In areas where snow accumulates, roof shingles can develop leaks as a result of ice dams which can form along the eaves of a roof. Ice dams form as the result of a differential temperature which occurs between the eaves of the roof and the interior sections of the roof. The temperature differential occurs when heat rises into the attic space. Under certain temperature conditions, snow collected on the roof surface will melt along the upper interior portions of the roof and then freeze when the liquid snow-melt reaches the cooler eave section of the roof. As can be seen in FIG. 1, the result is that a pool 1 of liquid water can form between the roof surface 2 and the ice dam 3. The ice dam 3 prevents the water from reaching the gutter 4 and draining away. Ultimately, the liquid water 1 can leak 5 through the roof surface 2, causing interior water damage to the structure. Ice dams can also occur as a result of frozen slush accumulating in gutters, also causing liquid to collect and leak through the roof.
In a typical roofing installation using asphalt shingles, an underlayer is first applied to the plywood deck of the roof. The underlayer may take the form of an asphalt saturated paper which is useful as a waterproofing member. Roofing shingles are applied on top of the underlayer with the seams of adjacent rows positioned in an offset relationship. In practice, a starter row or strip is begun at the roof eaves using self-sealing shingles. The end of the first shingle in the strip is trimmed such that, when it is placed on the deck, the cutouts of the first course of shingles will not be placed over the starter strip joints. The starter strip and the shingles are nailed to the eaves. Successive rows of shingles are then secured to the deck or roof using nails.
To ensure maximum protection against ice dams, membranes or metal flashing is installed wherever there is a possibility of icing, such as along the eaves of the roof. As noted above, ice dams are formed by the continual thawing and freezing of melting snow, or the backing up of frozen slush in gutters, which force water under the roofing, thereby causing damage to a structure's ceilings, walls, and insulation. The ice damming problem is most acute on low-slope roofs; that is, roofs with a slope of two inches (5.08 cm) to four inches (10.16 cm) per foot (30.48 cm).
Traditional eaves flashing has either been 50-pound coated felt or two layers of 15-pound saturated felt cemented together. The term "pound" is defined as the weight of the felt required to cover an area of 108 square feet. Typically, the asphalt used in the fifty-pound felt is not modified with rubber, and after aging, will not form a good seal around nails. Additionally, the installation of two layers of 15-pound saturated felt consumes undesirable amounts of time and also will not seal around nails.
The use of self-adhesive products, such as ice and water protective membranes, has now become commonplace. A major problem with these products is that they are slippery, especially when wet or covered with frost. Slippery surfaces upon roofs create significant safety hazards for roofing installers, especially since such surfaces tend to be at least one story above ground level.
In an attempt to reduce the slippery nature of ice and water protective membranes, separate methods have been developed. In the first method, granules have been embedded in an asphaltic composition or in polyethylene sheeting which is either embossed or coated. When positioned on an upper surface of the membrane, the granules provide a high-traction surface upon which a roofing installer can walk. Such membranes also offer reinforcement and/or structural integrity, and allow lap sealing. Unfortunately, the granular surfaced materials suffer from disadvantages in that the granules cannot all be embedded into the asphalt material, thereby providing some degree of loose granules which can render the surface slippery. Additionally, since the granules roughen the membrane surface, it becomes necessary to cement overlaps in order to render them watertight. Finally, the granules add weight to the membrane which increases handling difficulties and freight costs associated with the membranes.
As for the membranes which employ polyethylene sheeting, the polyethylene surface tends to be quite slippery, thereby raising safety concerns. Furthermore, membranes which use polyethylene sheeting tend to be very flexible, rendering them hard to handle and apply.
Thus, a need exists for a membrane material which provides a highly non-slip surface, excellent lap sealing, structural integrity and lower weight.